How people change the environment: forests, rivers, cities and pollution
Grade 9 Social Studies Worksheet - Building Confidence
Circle the best answer.
Read this first
Card A, forest facts (FAO, Global Forest Resources Assessment 2020)
The world has 4.06 billion hectares of forest, 31% of its land. Net forest loss was 7.8 million hectares a year in 1990–2000, 5.2 in 2000–2010 and 4.7 in 2010–2020. Deforestation, clearing forest for other land uses, was 12 million hectares a year in 2010–2015 and 10 million in 2015–2020. About 420 million hectares of forest were turned to other land uses from 1990 to 2020. Net loss is forest lost minus forest gained by planting and natural regrowth. Card B, chain: people clear forest for farmland, mines, reservoirs and cities; that gives more land for crops and other uses, and less forest, which puts wildlife habitats and the livelihoods of forest communities at risk.
Noah reads the word 'deforestation' on Card A. What does it mean?
- Planting trees on land that was cleared, so that the forest area grows back again over the years
- Clearing forest so the land can be used for something else, such as farms, mines or cities
- Forest lost minus forest gained by planting and natural regrowth, counted across a year or a decade
- Any loss of forest area, including forest that is lost and then regrows in the same place later
Pia sees 'net forest loss' on Card A. What does it measure?
- Forest cleared in a year, with the planting and regrowth left out of the count completely
- The share of the world's land that is forest, 31%, taken as a share of the whole world's land
- Forest lost minus the forest gained by planting and natural regrowth over the same years
- Forest gained by planting and regrowth minus the forest lost, so a larger gain makes net loss bigger
Net forest loss was 7.8, then 5.2, then 4.7 million hectares a year (1990–2000, 2000–2010, 2010–2020). What does Card A support, Ren asks?
- Forest loss ended in 2010, since each decade after the first showed a smaller loss than before
- Forest kept shrinking in each decade, but more slowly each time, so the loss slowed without ending
- Forest began growing back by 2020, since the net loss figures fell below 5 million hectares a year
- Deforestation fell from 7.8 to 4.7 million hectares a year, since the clearing slowed by that amount
Deforestation was 10 million hectares a year in 2015–2020, but net loss was 4.7 million a year in 2010–2020. Why is net loss smaller, Tala asks?
- The two periods differ, so net loss and deforestation cannot be compared with one another
- Net loss subtracts the forest gained by planting and natural regrowth from the forest cleared, so it is smaller
- Net loss counts just the forest cleared for cities, while deforestation counts clearing for farms, mines and reservoirs too
- Net loss is measured on a smaller forest area than deforestation is, so its figure comes out smaller
Card B follows a chain from clearing. Which pair of effects comes from the same act of clearing, Zee asks?
- More land for crops and other uses, and less forest, which puts habitats and livelihoods at risk
- More land for crops, and more forest, since the cleared land is soon replaced by planted trees
- More forest for habitats, and less land for crops, which puts the livelihoods of farmers at risk
- Less land for crops and more reservoirs, which put the livelihoods of forest communities at risk
A village clears forest for farmland. Which statement matches Card B, Bo asks?
- It gains land for crops with no cost, since the forest is replaced by fields that feed people near the village
- It has no clear gain or cost, since Card B names the uses and not the effects of clearing
- It loses land for crops but gains habitats, since cleared forest returns to wildlife in a few years
- It gains land for crops, while wildlife habitats and the livelihoods of forest communities are put at risk
Esme's note: 'The world lost 4.7 million hectares a year to deforestation in 2010–2020.' Which fix fits Card A?
- Change 4.7 to 31, since 31% of land is forest and so that figure describes the loss for the decade
- Change 'lost' to 'gained', since a figure that is below 5 million a year is a gain and not a loss
- Change 'deforestation' to 'net loss': deforestation was 12 then 10 million a year, with regrowth offsetting part
- Keep it, since net loss and deforestation both describe the forest that was cleared in those years, just under different names
Which statement about the world's forest is supported by Card A, Jun asks?
- Forest covers 4.06 percent of the world's land, since the figure given is 4.06 and is read as a percent, as the card states it
- About 420 million hectares, a third of the forest, were turned to other uses between 1990 and 2020
- Forest covers 31% of the world's land, which is nearly a third, so most land is something other than forest
- Forest covers most of the world's land, since 4.06 billion hectares is a very large area for forest
Deforestation was 12 million hectares a year in 2010–2015. About how much was cleared in those five years, Kira asks?
- About 60 million hectares, since a rate of 12 million a year for five years makes 60 million
- About 12 million hectares, since the figure on Card A is the amount for the whole period
- About 600 million hectares, since 12 million a year for five years is moved over by one place
- About 2 million hectares, since the rate fell from 12 to 10 million and the difference is 2 million
Why does a fall in net loss not show that people planted more trees, Luz asks?
- Net loss could fall because clearing fell, because gains rose, or both; the net figure alone does not say which
- Net loss measures clearing, so a fall in net loss is a fall in clearing and has nothing to do with planting, whatever the trees do
- Net loss falls when forest is lost faster, since a bigger loss means that a larger amount is subtracted
- Net loss falls when people plant more, since gains are the one thing the net figure moves with